1. Field of the Invention
This invention relates to spray heads and, more particularly, to spray heads for providing a fan-shaped spray from any one of a plurality of different sized holes.
2. Description of the Prior Art
For the aerial spraying of crops, the prior art spray nozzles all deliver a swirling pattern of the spraying liquid. The swirling, conical spray pattern extends downwardly from each nozzle, and a plurality of nozzles are generally aligned in a spaced apart relationship so that the swirling spray eventually overlaps to form some type of curtain. The overlapping sprays theoretically form into a curtain type configuration prior to the spray contacting the plants being sprayed. A typical nozzle of the prior art is shown in U.S. Pat. No. 3,596,835.
Another type of nozzle which also provides a conical, swirling type spray is disclosed in U.S. Pat. No. 2,388,093. The nozzles of both U.S. Pat. No. 3,596,835 and U.S. Pat. No. 2,388,093 include a plurality of holes or apertures, each of a different size, for producing different flow rates.
One of the problems with the prior art, swirling or conical type spray pattern, is that several feet are required before the cones of spray actually meet and blend into a solid, even sheet of spray. If the aircraft is not the absolutely correct height above the crops, then the spray pattern will not be relatively solid and an even spraying of the entire crop will not be accomplished.
One solution to the problem of providing a relatively solid, overlapping curtain of spray within a short distance after the spray liquid leaves the aircraft nozzles is to provide a fan-shaped spray pattern. It is known and understood that if a flow or stream of liquid is directed against a curved surface, a single curtain or fan-shaped spray of the liquid will result. Different apparatus have been developed in the prior art to provide a relatively flat spray, such as shown by U.S. Pat. No. 3,826,430. The apparatus of U.S. Pat. No. 3,826,430 is not, of course, directly related to an aircraft crop spraying system, but it does disclose a diffusing face adjacent an orifice through which a stream of liquid (water) flows. Another such apparatus which discloses a relatively flat, fan-shaped type of spray is shown in U.S. Pat. No. 1,288,122 and also in U.S. Pat. No. 580,251. However, none of the above-described patents relate to, or could be used, for aerial crop spraying. Moreover, none of the apparatus disclose the interchangeability of holes to provide a varied spray, depending on the size of the hole or orifice lined up with the stream of material to be sprayed.
The apparatus of the present invention provides both a curved surface for providing a fan-shaped spray of material, and a variable spray head having various sized orifices, each of which may be selectively aligned with a single port through which the stream of liquid flows for spraying onto a crop.